Methods To Control Organic Contaminants In Fibers Using Zeolites

ABSTRACT

Methods to control organic contaminants in fibers are described. One method involves contacting the fibers with a) at least one zeolite and optionally b) detackifier, or an ester hydrolyzing enzyme, or both, for a sufficient time and in a sufficient amount to control the organic contaminants present in the fibers. This method is effective to reduce stickies in paper mill furnish formed with recycled fibers. A method for pitch control in paper mill furnish formed with virgin fibers is also provided. Resulting paper products formed from the processed fibers are also described as well as methods to make them.

This application claims the benefit under 35 U.S.C. §119(e) of priorU.S. Provisional Patent Application No. 61/867,644, filed Aug. 20, 2013,which is incorporated in its entirety by reference herein.

BACKGROUND OF THE INVENTION

The present invention relates to papermaking processes and moreparticularly relates to controlling the organic contaminants present incertain types of fibers used to make paper or similar types of fibercontaining products.

Organic contaminants are present in paper pulp that tends to deposit onprocessing surfaces and equipment, causing maintenance problems andproduction inefficiencies. Organic contaminants of significant concernin this regard include “stickies” and pitch, with the former generallyassociated with recycled pulp sources while the latter with virgin pulpsupplies.

Conventional recycling of old paper products such as old newsprint, oldcorrugated containers, and mixed office waste is an important aspect ofpaper mills today due to environmental demands that many papercontaining products have a portion of recycled fibers contained withinthe paper product. Thus, paper mills are in a situation where therecycling of paper products is a necessity. However, the recycling ofthe paper products generally requires additional processing steps inorder to lead to fibers which can be useable in paper products.

Conventional recycling of old newspapers to obtain fibers comparable tothe type of fibers used to originally make the newsprint is known in theart as “de-inking,” and typically involves pulping, washing, usuallywith surfactants, screening, solubilizing insoluble contaminants usuallyby strong caustic treatments, washing, and bleaching of the fibers tocounteract the yellowing effects of caustic treatments.

Generally, the first step in conventional recycling is to separate thepaper into individual fibers with water to form a pulp slurry followedby removing ink and contaminants from the fibers by a combination ofvarious process steps, such as screening, centrifugal cleaning, washing,flotation, and the like. The screening and centrifugal cleaning stepremoves large contaminants, such as paperclips, staples, plastics, andthe like. The primary purpose of washing and flotation steps is tosolubilize and/or suspend contaminants in the water and to remove thecontaminants from the water. Surfactants and caustic agents are added tofacilitate the solubilization and separation of contaminants from thefibers. Once caustic agents are used, some yellowing of the fibers canoccur which may result in a need to bleach the fibers. The fibers areblended with, typically, virgin fibers and then used in the paper makingprocess for which the fiber properties are suitable. Recent developmentsin waste paper de-inking make use of enzymes to aid in the detachmentand removal of inks from the fibers. These processes describe the use ofparticular types of enzymes to facilitate ink removal without thenegative effects of caustic treatment on brightness along with the useof flotation to remove the agglomerated ink particles.

In the past, chemical additives such as caustic agents have been addedto remove organic contaminants, known as “stickies.” Stickies aregenerally adhesives, glues, hot melts, coatings, coating binders, inkresidues, de-inking chemicals, wood resins, rosin, and unpulped wetstrength resins that typically are present with the fiber to berecycled. These organic contaminants typically must be removed insubstantial quantities so that they do not affect the subsequentprocessing steps. There is always a desire in the paper making industryto develop new methods to remove such organic contaminants in moreeffective and environmentally friendly ways.

“Stickies” can be generally described as tacky, hydrophobic, pliableorganic materials found in recycled paper systems. Stickies have a broadrange of melting points and different degrees of tackiness dependentupon the composition of the stickies. Temperature, pH, concentration,size, and composition can affect the tackiness of stickies. The variablenature of stickies is one of the reasons that controlling or removingthem can be difficult and unpredictable. Also, the use of recycled fiberhas been increasing and is expected to continue growing, making stickiesa more significant problem.

Recycled paper fibers contain many components that when repulped inrecycle fiber plants become stickies. Recycled furnishes may have asmany as a dozen different types of stickies, each having its owncharacteristics. Sources of stickies may include any of the following:adhesives, hot melts, coating binders, ink residues, deinking chemicals,wood resins, rosin, pitch, and wet strength resins. The actual tackydeposits found on paper machines may be a combination of several ofthese organic contaminants as well as inorganic particles such as talc,clay, or calcium carbonate.

Stickies deposit on machine surfaces, fabrics, wires, felts, rolls anddryers lead to problems such as wet end breaks, pressroom breaks, dryersection breaks, holes, sheet defects, and high dirt counts. Thesedeposits and associated problems lead to a significant amount ofdowntime yearly. The cost of stickies has been estimated at over 500million dollars annually in the U.S., when considering the cost ofdowntime, chemical costs, production losses, rejected materials, andcustomer complaints.

There are various methods of removing stickies, mechanical and chemical.Mechanical methods include screening, cleaning, washing, floating, anddisperging, with each method designed to remove a different sizecontaminant. Screening typically removes larger or macro stickies(>0.004 inch or 100 microns). Forward and reverse cleaners can be used.Based on density differences using centrifugal force, forward cleanersremove contaminants heavier than water and reverse cleaners removeparticles lighter than water. This method removes more macro stickiesthan micro stickies. Floating removes intermediate size stickies (50-300microns), which are troublesome, because they are small enough to beaccepted by screening and cleaning but too large to be removed bywashing. In disperging, the stock is thickened, passed through a deviceat high temperature, pressure, and shear, which breaks organiccontaminants, including stickies, into smaller pieces.

Various chemical methods can be used. For instance, in pacification,additives like talc, clay, nonionic organic polymers, and otherinorganic particles are used to render the stickies less tacky. Indispersion, dispersants, surfactants, and solvents are used to makestickies smaller. Other methods use certain enzymatic treatments forpitch/stickies removal.

In fixation, the stickies are attached to the paper sheet by using acationic water soluble polymer, which adds charge to the stickies. Indisperse and fix, a dispersant is added first to reduce the size of thestickies and then a cationic polymer is used to fix the stickies ontothe sheet. With passivation, the use of dispersants, solvents, and lowmolecular weight cationic polymers makes the paper machine lesssusceptible to stickies.

In the past, the favored approach to remove stickies was to keep thestickies large in the stock prep area, so that the mechanical cleaningequipment can remove as many “stickies” as possible. Then, all remainingstickies should be dispersed either mechanically or chemically and fixedto the fiber, so that they can be sent out with the sheet.

Once as many stickies as possible are removed mechanically, the resthave in the past been dispersed mechanically, chemically, or by using acombination of the two. Once dispersed, polymer addition to stabilizethese particles in their smallest state has been used, so that theparticles will be retained on the sheet.

Measuring and controlling stickies in a recycled paper manufacturingprocess has always been a challenge. Variations in recycled paperquality and the trend to increase the amount of waste paper incorporatedinto each ton of pulp produced are each contributing factors that makethis challenge even more difficult to address. (Pulp and Paper FactBook, 2000). These variations make predicting the amount of stickiesthat are entering a mill's system troublesome. Once these stickies arein the system, the larger contaminants, or macrostickies, are oftenremoved mechanically. However, additional stresses on the screens andcleaner banks such as high furnish consistency, improper in-screendilution, improper reject rates, and differential pressure controlproblems will facilitate the acceptance of formed macrostickies(Gallagher, 1997). Macrostickies are defined as stickies that areretained on a 0.10 mm screen plate (Heise, 1998). These contaminantswhich come from adhesives, coatings, binders, and other materials areincorporated into the furnish during the pulping process, and willdeposit on forming fabrics, press felts, dryer fabrics, press sectionrolls, Uhle boxes, and calendar stacks (Douek, 1997). These materialsremain tacky in the paper making process, leading to the “stickies”label (Doshi, 1997). Once the materials are incorporated into thefurnish, they are difficult to remove, since they are deformable innature and are often close to the specific gravity of water. Thesephysical characteristics present a different screening and cleaningchallenge as these contaminants slip through screens and cleaners(Scholz, 1997) that are designed to allow water and fiber to beaccepted. The consequence of this fact is the acceptance ofmacrostickies into the post screening process.

Even if the cleaning and screening systems do perform properly and doremove most of the macrostickies, the remaining microstickies may causeproblems. The agglomeration of microstickies, stickies not retained on a0.1 mm screen, can lead to the formation of macrostickies which willthen deposit onto the machine and onto fabric surfaces (Doshi, 1997).Microstickies are not problematic as long as they remain small. However,they often agglomerate in the paper making process leading tomacrostickies formation

The cost of stickies deposition is a significant one. One sourceestimates the cost of the stickies problem to the industry in terms ofmachine downtime to be over $500 million annually for major recycledpaper grades (Friberg, 1997). Once macrostickies are present in thefurnish after the screening and cleaning systems, mechanical means ofremoving stickies have been exhausted. Preventing the agglomeration ofmicrostickies is also an issue in addition to the microstickies problem.In order to address each of these problems, a chemical control solutionis often required.

U.S. Pat. No. 6,471,826 B2 describes the use of a composition comprisingat least one esterase or lipase to reduce the concentration of stickiesin pulp and paper mill systems. U.S. Pat. No. 4,698,133 describes theuse of water-soluble cellulose derivatives to inhibit the deposition ofstickies on paper mill process equipment.

Pitch deposition on process equipment in paper making systems usingvirgin pulp supplies also can result in operational problems andproduction inefficiencies. Pitch is a naturally occurring matter in woodpulp. Pitch can deposit, for instance, on screens used in the processline to reduce their throughput, and/or on process control devices,rendering them inoperable, such as instrument probes. Deposition of thepitch can occur not only on metal surfaces in the system, but also onplastic and synthetic surfaces such as machine wires, felts, foils, uhleboxes and headbox components. Pitch deposits may also break offresulting in spots and defects in the final paper product which decreasethe quality of the paper. Surfactants, anionic polymers and copolymersof anionic monomers and hydrophobic monomers have been used extensivelyto prevent pitch deposition of metal soap and other resinous pitchcomponents. U.S. Pat. No. 5,074,961 describes the use of methylcellulosederivatives to inhibit the deposition of pitch on paper mill processequipment.

SUMMARY OF THE INVENTION

A feature of the present invention is to provide methods to controlorganic contaminants present in fibers that contain organiccontaminants. A further feature of the present invention is to provide amethod to process recycled and/or virgin pulp fibers in a manner suchthat the organic contaminants present in the recycled and/or virgin pulpfibers are controlled.

Additional features and advantages of the present invention will be setforth in part in the description which follows, and in part will beapparent from the description, or may be learned by practice of thepresent invention. The objectives and other advantages of the presentinvention will be realized and obtained by means of the elements andcombinations particularly pointed out in the written description andappended claims.

To achieve these and other advantages and in accordance with thepurposes of the present invention, as embodied and broadly describedherein, the present invention relates to a method to control organiccontaminants present in fibers containing organic contaminants. Themethod involves contacting fibers with a) at least one zeolite andoptionally b) at least one detackifier or at least one type of esterhydrolyzing enzyme, or both, for a sufficient time and in a sufficientamount to control organic contaminants present in the fibers.

In the present invention, a method can involve contacting recycledfibers with a) at least one zeolite and optionally b) at least onedetackifier, or at least one ester hydrolyzing enzyme, or both, for asufficient time and in a sufficient amount to control stickies presentin the recycled fibers. As an example, the combination of a) at leastone zeolite and optionally b) at least one detackifier, such as awater-soluble cellulose derivative, and/or an ester hydrolyzing enzyme,such as lipase, yields synergistic reductions in sticky amounts fromrecycled fibers, such as compared to the use of clay alone, detackiferalone, and/or clay with same detackifier.

Amongst other benefits and advantages, the combination of a) at leastone zeolite and optionally b) at least one detackifier, or at least oneester hydrolyzing enzyme, or both, gives improved control of stickies.The method is effective to reduce stickies in paper mill furnishes,e.g., which utilize old newspapers, old corrugated containers, and mixedoffice waste, and the like.

Also, in the present invention, a method can involve contacting virginfibers with a) at least one zeolite and optionally b) at least onedetackifier, such as at least one type of water-soluble cellulosederivative, or at least one type of ester hydrolyzing enzyme, or both,and optionally at least one type of lipoxygenase, for a sufficient timeand in a sufficient amount to control the pitch present in the virginfibers.

The present invention further relates to controlling organiccontaminants from fibers in papermaking systems. The method includestreating water in a clarifier, or, immediately prior to the clarifier ina papermaking system, with a) at least one zeolite and optionally b) atleast one detackifier, or at least one ester hydrolyzing enzyme, orboth, for a sufficient time and in sufficient amounts to control theorganic contaminants present in the water.

The benefits of the methods of the present invention include, forexample, reduced downtime, increased machine runnability, reducedfurnish cost, improved converting efficiency, increased brightness,improved effective residual ink concentration, improved sheet quality,and/or reduced solvent usage. The methods can be cost effective ascompared to conventional stickies or pitch control programs.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory onlyand are only intended to provide a further explanation of the presentinvention, as claimed. The accompanying drawings, which are incorporatedin and constitute a part of this application, illustrate severalfeatures of the present invention and together with the writtendescription, serve to explain the principles of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a bar graph depicting the reduction in organic contaminants,based on ppm organic contaminants for a variety of formulationsincluding a control and comparative formulations, and formulations ofthe present invention.

FIG. 2 is a bar graph depicting the ppm of stickies for large stickies,medium stickies, and small stickies for several formulations and acontrol using Pulmac testing.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The present invention relates to methods to control organic contaminantspresent in fiber containing organic contaminants by treating fibers witha) at least one zeolite and optionally b) at least one detackifier, orat least one ester hydrolyzing enzyme, or both, and optionally alsolipoxygenase. The fiber can be cellulose fibers, such as recycledfibers, virgin wood cellulose fibers, or combinations thereof

Processing of Recycled Fibers.

A method is provided for contacting fibers, e.g., recycled fibers, witha combination of a) at least one zeolite, and optionally b) at least onedetackifier or at least one ester hydrolyzing enzyme(s), or both, whichhas been found to provide improved stickies control. Synergistic levelsof stickies reduction may be achieved where at least one zeolite, and atleast one detackifier, and/or at least one ester hydrolyzing enzyme,such as a lipase, are used. The method reduces the amount of stickies inpaper mill furnish and/or detackifies the remaining stickies so thedeposition of the remaining stickies is inhibited.

The recycled fibers may be obtained from a variety of paper products orfiber containing products, such as paperboard, newsprint, sanitary andother paper products. These products may comprise, for example, oldcorrugated containers (OCC), old newsprint (ONP), mixed office waste(MOW), or combinations thereof. These types of paper containing productstypically contain large amounts of organic contaminants which arepresent in the paper products. When these types of paper products arerecycled, these organic contaminants are present along with the fibersformed during the pulping stage of a paper making process. These organiccontaminants, if not substantially removed, can severely interfere withsubsequent stages in the paper making process by affecting the qualityof the resulting sheets of paper formed and/or effecting the machineryused to form the paper. Accordingly, the removal of such organiccontaminants is important to the paper making process when such organiccontaminants are present in fibers.

For purposes of the present invention, examples of organic contaminantsinclude what is known in the industry as “stickies” and include, but arenot limited to, synthetic polymers resulting from adhesives and thelike, glues, hot melts, coatings, coating binders, ink residues,de-inking chemicals, wood resins, rosin, pressure sensitive binders andunpulped wet strength resins. These type of materials are typicallyfound in paper containing products, such as newsprint, corrugatedcontainer, and/or mixed office waste. These organic contaminants canhave polymers present, such as styrene butadiene rubber, vinylacrylates, polyisoprene, polybutadiene, natural rubber, ethyl vinylacetates, polyvinyl acetates, ethylvinyl alcohols, polyvinyl alcohols,styrene acrylates, and/or other synthetic type polymers.

In the present invention, these organic contaminants can be controlledby contacting the fiber containing the organic contaminants with atleast one zeolite and optionally at least one detackifier and/or atleast one ester hydrolyzing enzyme for a sufficient time and in asufficient amount to control the organic contaminants present in thefiber. The at least one zeolite, and optionally at least one detackifierand/or at least one enzyme can disperse or convert the organiccontaminants to organic species that do not affect the paper makingprocess. For instance, the polyvinyl acetates can be dispersed and/orconverted to polyvinyl alcohols, which do not affect the paper makingprocess. This manner that the compositions achieve control of organiccontaminants is quite different from collecting contaminants byflotation.

Zeolite.

In the methods of the present invention, one or more types of at leastone zeolite are used. The at least one zeolite is in particle orparticulate form. The at least one zeolite can be present in a liquidsuspension. The liquid suspension can contain the at least one zeolitealone or it can contain one or more of the other treatment chemicalsused in the methods of the present invention, such as the detackifier(s)and/or enzyme(s), and can have other optional components. The at leastone zeolite can have any particle size distribution. For instance, theat least one zeolite can have an average or median particle size of 100microns or less, such as 80 microns or less, 60 microns or less, 50microns or less, 40 microns or less, 30 microns or less, 25 microns orless, 20 microns or less, 15 microns or less, 10 microns or less, 7microns or less, or 5 microns or less. For instance, the at least onezeolite can have a median particle size of from about 5 microns to about50 microns, from about 5 microns to about 45 microns, from about 5microns to about 40 microns, from about 5 microns to about 20 microns,and the like. The at least one zeolite is commercially available from avariety of sources including, but not limited to, ZEO Inc. More specificbrands are Z-Ultra and the like. The at least one zeolite can be used ina natural or synthetic particulate form milled to the desired particlesize, or it can be calcined, or otherwise treated. The at least onezeolite can be used in the present invention in a treatment amount offrom about 0.1 kg to about 20 kg per metric ton of dried pulp fiber.

The zeolite can be natural or synthetic (for instance from a sol-gelprocess). The zeolite can be considered a molecular sieve. The classicaldefinition of a zeolite is a crystalline, porous aluminosilicate.However, zeolite can include some relatively recent discoveries ofmaterials virtually identical to the classical zeolite, but having oxidestructures with elements other than silicon and aluminum. Zeolites thusinclude porous oxide structures that have well-defined pore structureswith a degree of crystallinity.

As an option, the zeolite, such as natural zeolite, can be modifiedthrough crosslinking, and/or grafting, and/or surface coating, and/orimpregnation and/or adsorption, or any combinations thereof. Forexample, a zeolite, can be treated with a cationic surfactant, which canoptionally improve its adsorption properties.

The zeolite can be considered a particular microporous, aluminosilicatemineral. Examples include, but are not limited to, analcime, chabazite,clinoptilolite, heulandite, natrolite, phillipsite, natrolite, andstilbite. Further examples include, Zeolite A and faujasite. Otherexamples include, using the zeolite structural group (Nickel-Strunzclassification):

-   -   09.GA.—Zeolites with T₅O₁₀ units—the fibrous zeolites        -   Natrolite framework (NAT): gonnardite, natrolite, mesolite,            paranatrolite, scolecite, tetranatrolite        -   Edingtonite framework (EDI): edingtonite, kalborsite        -   Thomsonite framework (THO): thomsonite-series    -   09.GB.—Chains of single connected 4-membered rings        -   Analcime framework (ANA): analcime, leucite, pollucite,            wairakite        -   Laumontite (LAU), yugawaralite (YUG), goosecreekite (GOO),            montesommaite (MON)    -   09.GC.—Chains of doubly-connected 4-membered rings        -   Phillipsite framework (PHI): harmotome, phillipsite-series        -   Gismondine framework (GIS): amicite, gismondine, garronite,            gobbinsite        -   Boggsite (BOG), merlinoite (MER), mazzite-series (MAZ),            paulingite-series (PAU), perlialite (linde type L framework,            zeolite L, LTL)    -   09.GD.—Chains of 6-membered rings—tabular zeolites        -   Chabazite framework (CHA): chabazite-series, herschelite,            willhendersonite and SSZ-13        -   Faujasite framework (FAU): faujasite-series, linde type X            (zeolite X, X zeolites), linde type Y (zeolite Y, Y            zeolites)        -   Mordenite framework (MOR): maricopaite, mordenite        -   Offretite-wenkite subgroup 09.GD.25 (Nickel-Strunz, 10 ed):            offretite (OFF), wenkite (WEN)        -   Bellbergite (TMA-E, Aiello and Barrer; framework type EAB),            bikitaite (BIK), erionite-series (ERI), ferrierite (FER),            gmelinite (GME), levyne-series (LEV), dachiardite-series            (DAC), epistilbite (EPI)    -   09.GE.—Chains of T₁₀O₂₀ tetrahedra        -   Heulandite framework (HEU): clinoptilolite,            heulandite-series        -   Stilbite framework (STI): barrerite, stellerite,            stilbite-series        -   Brewsterite framework (BRE): brewsterite-series    -   Others        -   Cowlesite, pentasil (also known as ZSM-5, framework type            MFI), tschernichite (beta polymorph A, disordered framework,            BEA), linde type A framework (zeolite A, LTA).

There are no limitations to the molecular structure, surface area,surface charge density, and/or cation exchange capacity (CEC) of thezeolite to be used in the present invention. Some useful parametersinclude, but are not limited to:

-   -   Specific gravity: 0.7 to 1, such as about 0.85 s.g.    -   Appearance: Grey to green    -   Melting point: >1200 C    -   Particle size: avg size of 1 to 10 microns, such as 2 to 7        microns, or 3 to 6 microns, such as about 4.5 micron average.    -   CEC: 2.0˜5.6    -   Void volume (pore space): 15-50%.    -   Any one, two, three, four, or more of these parameters in any        combination can be present in the zeolite used in the present        invention, as an option.

For purposes of the present invention, the at least one zeolite is not aclay or kaolinite or bentonite, montmorillonite, wollastonite, or talcor similar types of minerals.

Detackifiers.

The methods of the present invention can use optionally at least onedetackifier, which can be or include one or more derivatives ofcellulose as one of the co-ingredients. The materials that are effectivefor this application are water soluble derivatives of cellulose. Lowerand higher alkyl (e.g., C₂, C₃, C₄, C₅, C₆, C₇, C₈, C₉, or C₁₀ andhigher) ether derivatives of cellulose and/or alkyl linkages other thanethers can be used so long as they are water soluble. Water-solublederivatives of cellulose are commercially available, e.g., as methylcellulose, hydroxyethyl methyl cellulose, hydroxypropyl methylcellulose, cetyl hydroxyethylcellulose and hydroxybutyl methylcellulose. Non-substituted or substituted forms of these celluloses maybe used.

Methyl ether derivatives (or alkyl ether derivatives) of cellulose canbe made by reacting cellulose with the appropriate reagent in thepresence of caustic soda. Methyl cellulose can be made using methylchloride, hydroxyethyl methyl cellulose can be made using ethylene oxideand methyl chloride, hydroxypropyl methyl cellulose can be made usingpropylene oxide and methyl chloride and hydroxybutyl methyl cellulosecan be made using butylene oxide and methyl chloride. Among these threetypes, there are variations in molecular weight ranging from about10,000 to about 246,000 which corresponds to a degree of polymerizationof from about 53 to about 1,280 anhydroglucoside units. The number ofsubstitution groups on the anhydroglucoside units of the cellulosepolymer can affect the solubility properties, but all levels ofsubstitution that are water soluble are part of this invention. Thecellulose derivatives may contain methyl ether substitution, or hydroxylethyl ether substitution, or hydroxyl propyl methyl ether substitutionor hydroxyl butyl ether substitution or cetyl hydroxylethyl or othergroups may be added that do not affect the efficacy of the cellulosederivative for this purpose. Commercially available water-solublecelluloses that can be used in compositions of the present inventioninclude Methocel products, such as Methocel F50, which ishydroxypropylmethylcellulose, Methocel F15AV, which is methyl cellulose,and Cellosize QP-1500-H hydroxyethyl cellulose, which is hydroxyethylmethyl cellulose, all available from Dow Chemical Co., Midland Mich. andNatrosol 330 Plus which is cetyl hydroxyethylcellulose, available fromAshland Inc., Wilmington, Del., and is described in U.S. PublishedPatent Application No. 2004/0231816. The water-soluble cellulosederivatives as encompassed by the present invention are generallynonionic in nature and the alkyl group of the alkyl ether moiety can beunsubstituted or substituted. Preferred amounts of the water-solublecellulose derivatives are from about 0.002 lbs. to about 2 lbs. per tonof dry fiber treated, and more preferably from about 0.004 to about 1lb. per ton of dry fiber treated, and most preferably from about 0.01 toabout 0.4 lbs. per ton of dry fiber treated. Alkyl ether celluloses canbe made in the same manner. More than one type of methyl (or alkyl)ether cellulose derivative can be used, such as two, three, or fourtypes. The methyl (or alkyl) ether cellulose derivatives can bepre-combined beforehand or added separately or introduced in any orderin forming the composition and/or introducing the composition (orcomponents thereof) in the papermaking process. In the alternative or inaddition, other detackifiers can be used. The amount of the detackifiersthat can be used in the present invention would be the same amounts asset forth above for the water-soluble cellulose derivatives.

Ester Hydrolyzing Enzymes.

In the methods of the present invention, at least one ester hydrolyzingenzyme can be optionally used, and can be used at a high concentrationof ester hydrolyzing enzymes. Esterase, lipase, and cutinase arenon-limiting examples of ester hydrolyzing enzymes that may be usedsingly or in any combinations thereof in the methods of the presentinvention. Esterases are enzymes that cleave triglycerides (viz., fatsor lipids) or esters into carboxylic acids (fatty acids) and mono- anddi-glycerides. Lipases are hydrolytic enzymes that act upon the esterbond of neutral lipids and phospholipids. Lipases hydrolyzetriglycerides, or fats, to glycerol and fatty acids. Cutinases arehydrolytic enzymes that degrade cutin, the cuticular polymer of higherplants, which is a polyester composed of hydroxy and epoxy fatty acids.Fatty acids of cutin are usually n-C₁₆ and n-C₁₈ and contain one tothree hydroxyl groups.

Lipase can be derived or isolated from pancreatic sources (e.g.,pancreatic lipase) or from various fungi and/or bacteria, and/or othermicroorganisms. Examples include, but are not limited to,triacylglycerol acylhydrolase and triacyl glycerol lipase. Also, anylipase or esterase capable of hydrolyzing triglycerides to glycerol andfatty acids can be used. Commercially available products containingesterase or lipase can be used. For instance, Optimyze®, Optimyze Plus,Buzyme® 2528, Buzyme® 2515 and Buzyme® 2517 can be used which areproducts available from Buckman Laboratories International, Inc. Theseproducts can combine the lipase or esterase enzyme with solvents andsurfactant for stability. Products containing such enzymes as ResinaseHT, Resinase A2X, Novocor ADL, Pancreatic Lipase 250, Lipase G-1000,Greasex 50L, and Greasex 100L products can be used in the methods of thepresent invention. Such products are available from such commercialsources as Genencor, Novo Nordisk, and Novozymes, Inc. Esterase sourcesare available as products designated as NS51032 or NS51060, which arecommercially made by Novozymes Inc. The esterase or lipase described inU.S. Pat. Nos. 5,507,952 and 5,356,800 and in U.S. Patent ApplicationPublication Nos. 2003/0051836 and 2004/0226672 can be used in thepresent invention and these patents are incorporated in their entiretyalong with any other patent publications mentioned in this application,by reference herein. A lipolytic enzyme can be used in the presentinvention. The ester hydrolyzing enzymes can generally be used in anyform, such as liquid form or solid form. Preferably, the amount of esterhydrolyzing enzyme used in the methods of the present invention are asufficient amount to control the organic contaminants present in thefiber. The enzyme used in the present invention can have any amount ofactivity. For instance, the activity can be at least 5.0 LU/Gm/min, suchas at least 10 LU/Gm/min, or at least 15 LU/Gm/min, for instance from15.0 to 30.0 LU/Gm/min defined as lipase units per gram per minute(LU/gm/min). The lipases used in the present invention can have thisactivity, for instance, the triacylglycerol lipase and other lipases.For instance, Resinase A2X lipase from Novozyme has activity of about15.0 to 20.0 LU/Gm/min defined as lipase units per gram per minute(LU/gm/min). As another example, a cutinase can be evaluated based onits vinyl acetate esterase activity for de-esterifying polyvinylacetate.Therefore, the cutinase can be assayed as its ability to liberate orproduce millimoles of acetic acid per gram per minute. This activity canbe equal to at least 10 mmol/gm/min, or at least 15 mmol/gm/min, or atleast 20 mmol/gm/min of liberated acetic acid. For example, Optimyzeactivity can be equal to 21.0 to 23.0 mmol/gm/min of liberated aceticacid. Preferred (total) amounts of ester hydrolyzing enzyme are fromabout 0.005 lbs. to about 4 lbs. per ton of dry fiber treated, and morepreferably from about 0.01 to about 2 lbs. per ton of dry fiber treated,and most preferably from about 0.05 to about 0.5 lbs. per ton of dryfiber treated. More than one enzyme can be used, such as two, three,four, or more. The one or multiple enzymes can be added as part of apre-mixture, added separately, or added in any order in the methods ofthe present invention.

The ester hydrolyzing enzyme may be stabilized esterase and/or lipasecompositions using the formulations described in U.S. Pat. Nos.5,356,800 and 5,780,283, incorporated in their entirety by referenceherein. At least one polymer can be added together with the compositioncontaining the water-soluble cellulose derivative and ester hydrolyzingenzyme at about the same time. Alternatively or additionally, one ormore polymers can be added before or after the introduction of theenzyme(s). For instance, the polymer(s) can be added one hour or lessbefore or after introduction of the enzyme(s) to the fiber. The polymercan be a water soluble polymer, such as a cationic water solublepolymer. Examples of such polymers include, but are not limited to,epichlorohydrin/dimethylamine polymers (EPI-DMA) and cross-linkedsolutions thereof, polydiallyl dimethyl ammonium chloride (DADMAC),DADMAC/acrylamide copolymers, ionene polymers, and the like. Examples ofionene polymers include, but are not limited to, those set forth in U.S.Pat. Nos. 5,681,862 and 5,575,993, both incorporated in their entiretiesby reference herein. Further, the polymers set forth in U.S. Pat. No.5,256,252 can be used as well and this patent is incorporated in itsentirety by reference herein. The polymer if used in the methods of thepresent invention can be used in any amount and preferably in dosageranges of from about 0.1 to about 15 pounds per ton of dry fibertreated, more preferably from about 0.25 pounds to about 10 pounds perton of dry fiber treated, and more preferably from about 1 pound toabout 5 pounds per ton of dry fiber treated.

For purposes of the present invention, controlling organic contaminantspresent in fibers having organic contaminants is understood as one ormore of the following: reducing the size of contaminant particles,reducing the number or amount of measurable particles present, and/orreducing the tackiness of the organic contaminants. Preferably, whencontrolling organic contaminants using the methods of the presentinvention, all of these reductions occur. Preferably, the reduction ofthe size of contaminant particles is by at least about 5%, morepreferably by from about 10% to about 75% as compared to when notreatment is used, or compared to clay used alone or clay withdetackifier. Similarly, the reduction in the number or amount of organiccontaminants present in the fiber is reduced by at least about 5%, andmore preferably by from about 10% to about 75% when compared to fiberswhich have not been treated at all. Also, the reduction of tackiness ofthe organic contaminants is preferably reduced by at least about 5%, andmore preferably by from about 10% to about 75% when compared to fiberswhich have not been treated at all.

As an option, conventional paper treatment chemicals or ingredients suchas, but not limited to, one or more surfactants, solvents, suspensionaids, fillers, chelants, preservatives, buffers, water, and/orstabilizers, and the like can be used. These additional ingredients canbe present in conventional amounts.

In the methods of this present invention, the at least one zeolite andoptionally at least one detackifier and/or at least one esterhydrolyzing enzyme can be introduced at any point in the processing ofthe fiber containing organic contaminants as part of a paper makingprocess. Generally, the at least one zeolite and optionally at least onedetackifier and/or ester hydrolyzing enzyme is introduced or broughtinto contact with the fiber containing the organic contaminants in anyfashion. For instance, if the fiber containing the organic contaminantsoriginates from products to be recycled, the at least one zeolite andoptionally at least one detackifier and/or ester hydrolyzing enzyme canbe introduced prior to the pulping stage, during the pulping stage,and/or after the pulping stage. If introduced prior to the pulpingstage, typically, they will be introduced such as by spraying or othermeans, onto the paper containing product which are going to beintroduced into the pulper. Also, or alternatively, they can be presentor introduced into the pulper during the pulping stage which can be byany conventional pulping technique such as mechanical pulping, fullchemical pulping, or combinations thereof. They can be introduced duringthe stock preparation stage of the paper making process. The contacttime with the fibers containing organic contaminants can be maximized.The at least one zeolite and at least one detackifier, and/or at leastone ester hydrolyzing enzyme generally are used in a manner providingsufficient reaction time, minimal concentration of oxidizers, and asuitable pH and temperature ranges. There is no need to denature theenzymes. The optimum pH for enzyme activity may vary for differentenzymes. In general, the at least one zeolite with or without at leastone detackifier and/or ester hydrolyzing enzyme is generally effectiveover a pH range of about 6.8 to about 9.5, and a temperature range ofbetween about 4 and about 65° C. Preferably, the contact time should besufficient to control the organic contaminants present with the fiberssuch that organic contaminants are substantially controlled. Preferably,the contact time is from about 1 min. to about 8 hours, more preferablyfrom about 10 min. to about 4 hours, and most preferably from about 20min. to about 2 hours.

The at least one zeolite and optionally at least one detackifier and/orester hydrolyzing enzyme can be introduced or brought into contact withthe fiber containing organic contaminants at the thick stock storagestage and/or prior to the flotation de-inking stage. The at least onezeolite with or without at least one detackifier and/or esterhydrolyzing enzyme can be introduced after the flotation stage in thepaper making process. The at least one zeolite with or without at leastone detackifier and/or ester hydrolyzing enzyme can be introduced afterthe flotation stage and before the paper machine headbox. In some papermaking processes, there is no flotation step, such as with the recyclingof OCC. Thus, the at least one zeolite and at least one detackifierand/or ester hydrolyzing enzyme can be added at or after the pulperand/or at or before the headbox, and/or can be added in the papermachine white water.

The manner in which the at least one zeolite and optionally at least onedetackifier and/or ester hydrolyzing enzyme are introduced or broughtinto contact with the fiber containing the organic contaminants can bein any fashion, such as by injection points, pouring into the area to betreated, and/or using repulpable bags of dry or liquid enzymes. Theintroduction of the treatment chemicals can be immediate, slow release,timed release, intermittent, and/or continuous.

In the methods of the present invention, the treatment chemicals can beintroduced at multiple points or at just one point of the paper makingoperation. In addition, more than one type of at least one zeolite,detackifier (if used), and/or ester hydrolyzing enzyme (if used) can beused, mixtures can be used, or any other variations as long as at leastone at least one zeolite with or without at least one detackifier and/orester hydrolyzing enzyme are introduced in some fashion in order tocontrol organic contaminants present in fibers having organiccontaminants. The treatment chemicals (or mixture) can be pre-formedprior to introducing to the papermaking operation, or the individualcomponents can be added separately or can be pre-combined and added to afeed line, or can be added in any order or combination. The addition canbe by batch, continuously, semi-continuously, or any combinationthereof. The treatment chemicals may or may not be diluted with freshwater or process water.

In the methods of the present invention, the controlling of the organiccontaminants present in fibers having organic contaminants can beincorporated into any paper making operation, including tissue paper.Typically, the remaining aspects of the paper making operation as isknown to those skilled in the art can be used in order to form paperproducts. Thus, the conventional additive materials used with papermaking pulps during stock preparation can be used as well in the presentinvention. Continuous or non-continuous paper making machines can thenconvert aqueous suspensions of fibers and other ingredients into drysheets of paper using such conventionally known operations which involveFourdrinier machines, twin wire machines or cylinder machines or otherpaper making devices. Subsequent treatments of the sheets of paper toachieve the desired characteristics such as machine calendering and/orcoating of the papersheets and the like can also be used in the presentinvention. Regarding the tissue paper, a method of manufacturing crepepaper can be used, including soft, absorbent tissue paper webs, andparticularly to modes of creping of such webs to attain adequatesoftness and adhesive characteristics while minimizing operationaldifficulties. According to the present invention, a thin paper web isformed from a slurry of water and treated fiber using a conventional webforming technique. The web is then dewatered and preferably is at leastpartially dried. The web is then conveyed, for example, carried on afabric, to a large preferably steam-heated rotary drum dryer, referredto herein and elsewhere as a Yankee dryer. The web commonly enters thedryer at a circumferential dryer position that is preferably at leastabout halfway around, and more preferably at least about 75% around, thecylindrical dryer with respect to the zone of web de-contact from thedrum. The de-contact zone is equipped with a creping blade against whichthe web abuts so as to be pushed backwardly upon itself and attain thewell-known tissue crepe paper structure. Other tissue drying systemssuch as Through Air Drying (TAD) may be used. Creping systems, methods,and adhesives are described in the following U.S. Pat. Nos. which areincorporated herein in their entireties by reference: U.S. Pat. Nos.3,640,841; 4,304,625; 4,440,898; 4,788,243; 4,994,146; 5,025,046;5,187,219; 5,326,434; 5,246,544; 5,370,773; 5,487,813; 5,490,903;5,633,309; 5,660,687; 5,846,380; 4,300,981; 4,063,995; 4,501,640;4,528,316; 4,886,579; 5,179,150; 5,234,547; 5,374,334; 5,382,323;5,468,796; 5,902,862; 5,942,085; 5,944,954; 3,879,257; 4,684,439;3,926,716; 4,883,564; and 5,437,766.

Although not desiring to be bound by theory, it is believed that thecombined at least one zeolite with or without detackifier and/or esterhydrolyzing enzyme used in methods of the present invention reduceand/or inhibit stickies problems by at least one or more of thefollowing mechanisms or effects, including aiding in separating themfrom the wastepaper; removing them from the fiber and the de-inkingprocess; preventing agglomeration of residual stickies in the pulp;preventing deposition on the fabric, felt and dryer; and/or retainingmicroscopic stickies in the sheet at a size too small to causemanufacturing or converting problems.

Processing of Virgin Fibers.

A method is also provided for contacting fibers, particularly virginfibers, with at least one zeolite optionally with at least onedetackifier and/or one or more ester hydrolyzing enzymes, and optionallylipoxygenase, which has been found to improve control of pitch. Esterhydrolyzing enzymes, such as lipase, can be used to reduce theconcentration of fatty esters in pulp and paper mill systems. Fattyesters are quite prone to deposit in pulp and paper mills and it isexpected that by reducing the fatty ester content, that reduceddeposition will be seen. However, this has not proven to be the case.Fatty acids which are the reaction product of the action of the enzymewith fatty esters often deposit, which will cause the mill to haveoperational and quality problems. The combination of at least onezeolite with or without at least one detackifier and/or esterhydrolyzing, and optionally lipoxygenase enzymes, can unexpectedlyprovide improved pitch control. These combinations reduce the amount ofpitch in the paper mill furnish and also detackifies the remaining pitchso the deposition of the remaining pitch is inhibited. The utility ofthe treatment process is not believed dependent upon whether the pulp isderived from softwood, hardwood or blends thereof. For purposes of thisapplication, virgin fiber refers to cellulosic fiber other than recycledfiber, and can include bleached or unbleached Kraft, sulfite pulp orother chemical pulps, and groundwood (GW) or other mechanical pulps suchas, for example, thermomechanical pulp (TMP), or chemical-mechanicalpulps, for example, chemical thermomechanical pulp (CTMP), AlkalinePeroxide Mechanical Pulp (APMP).

Lipoxygenases.

Lipoxygenases are iron-containing enzymes that catalyze thedioxygenation of polyunsaturated fatty acids to form fatty acidhydroperoxides. Lipoxygenases are found in plants and animals. Preferredamounts of the lipoxygenase are from about 0.004 lbs. to about 4 lbs.per ton of dry fiber treated, and more preferably from about 0.01 toabout 2 lbs. per ton of dry fiber treated, and most preferably fromabout 0.05 to about 0.5 lbs. per ton of dry fiber treated. Thewater-soluble cellulose and ester hydrolyzing enzymes may be used inthis composition that further includes lipoxygenase in respective rangeamounts that are similar to those described above for the compositionpreferably used in treating recycled fiber. More than one lipoxygenasecan be used, such as two, three, or four or more. The lipoxygenase canbe pre-combined with the water-soluble cellulose derivative and/or theester hydrolyzing enzyme, or can be added separately to a feed stream orto the pulp stream or elsewhere.

The at least one zeolite optionally with at least one detackifier and/orester hydrolyzing enzymes, and optional lipoxygenase enzymes, areeffective in controlling pitch deposition in paper making systems, suchas Kraft, acid sulfite, groundwood and other mechanical pulp papermaking systems. For example, pitch deposition in the brown stock washer,screen room and decker systems in Kraft pulp making processes can becontrolled. The term “paper making system” is meant to include all pulpprocesses. Generally, it is thought that these polymers can be utilizedto prevent pitch deposition on all wetted surfaces from the pulp mill tothe reel of the paper machine under a variety of pH's and conditions.More specifically, the present invention effectively decreases thedeposition of metal soap and other resinous pitch components not only onmetal surfaces, but also on plastic and synthetic surfaces such asmachine wires, felts, foils, uhle boxes and headbox components. Thetreatment chemicals of the present invention can be added to the pulp atany stage of the paper making system. The treatment chemicals can beadded in dry particulate form or as an aqueous suspension. The effectiveamount of these compositions to be added depends on the severity of thepitch problem which often depends on a number of variables, includingthe pH of the system.

For purposes of the present invention, controlling pitch present infibers having pitch is understood as one or more of the following:reducing the size of pitch particles, reducing the number or amount ofmeasurable particles present, and/or reducing the tackiness of thepitch. Preferably, when controlling pitch using the methods of thepresent invention, all of these reductions occur. Preferably, thereduction of the size of pitch particles is by at least about 5%, morepreferably by from about 10% to about 75% as compared to when notreatment chemicals are present. Similarly, the reduction in the numberor amount of pitch present in the fiber is reduced by at least about 5%,and more preferably by from about 10% to about 75% (e.g., by weight)when compared to no treatment chemicals are present. Also, the reductionof tackiness of the pitch is preferably reduced by at least about 5%,and more preferably by from about 10% to about 75% when compared tofibers which have not been treated with treatment of the presentinvention.

The present invention is also effective in treating water at a clarifierstage in a papermaking process. More particularly, the control oforganic contaminants from fibers in a papermaking system involvestreating the water in a clarifier or clarifier stage or immediatelyprior to the clarifier or clarifier stage. The treatment can be the sameas above, namely, with at least one zeolite with or without at least onedetackifier and/or at least one ester hydrolyzing enzyme, for asufficient time and in a sufficient amount to control the organiccontaminants present in the water. The examples of treatment amount ofeach treatment chemical, and all of the other options with regard to theprevious methods apply equally here.

For purposes of the present invention, the term “treatment chemicals”includes a) at least one zeolite and optionally b) at least onedetackifier and/or at least one ester hydrolyzing enzyme, and,optionally, c) any other conventional component.

The present invention further relates to paper or paperboard or tissuepaper or creped paper made from the processes of the present invention.The present invention further relates to a wet web paper or tissue(e.g., the paper or tissue existing prior to the dryer stage), whichcomprises pressed pulp fibers, at least at least one zeolite. Theamounts present in the pressed pulp fibers can be as follows for eachcomponent:

-   -   At least one zeolite: 0.2 to 40#/ton (dry fiber)    -   Detackifier: 0 to 5#/ton (dry fiber)    -   Ester hydrolyzing enzyme: 0 to 3 #/ton (dry fiber).

As an option, the enzyme, if used, can be introduced once pulp ispresent in the pulper. The enzyme, if used, can be introduced prior tothe at least one zeolite and/or at least one detackifier (if used). Asan option, all of the treatment chemicals combined can be added at asingle time as part of a liquid suspension. Optionally, each treatmentchemical can be introduced separately as a dry component or as a liquidsuspension. The treatment chemicals can be fed batchwise,semi-batchwise, semi-continuously, or continuously.

The present invention includes the followingaspects/embodiments/features in any order and/or in any combination:

1. The present invention relates to a method for controlling depositionof organic contaminants from fibers in paper making systems, comprisingcontacting said fibers with a) at least one zeolite and optionally b) atleast one detackifier, or at least one ester hydrolyzing enzyme or both,for a sufficient time and in a sufficient amount to control the organiccontaminants present in the fibers.2. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is said at least one ester hydrolyzing enzyme.3. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is at least one detackifier.4. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is at least one ester hydrolyzing enzyme andat least one detackifier.5. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and detackifier are present togetheras a liquid suspension and added to a pulp slurry containing saidfibers.6. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite, detackifier, and ester hydrolyzingenzyme are present together in a liquid suspension and added to a pulpslurry containing said fibers.7. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and ester hydrolyzing enzyme arepresent together in a liquid suspension and added to a pulp slurrycontaining said fibers.8. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and optionally b) are added to a pulpslurry containing said fibers prior to a forming stage.9. The method of any preceding or following embodiment/feature/aspect,wherein said organic contaminants comprise synthetic polymers fromadhesives, glues, hot-melts, coatings, coating binders, de-inkingchemicals, ink residues, wood resins, rosin, contact adhesive binders,unpulped wet strength resins, pitch, or combinations thereof.10. The method of any preceding or following embodiment/feature/aspect,wherein said fibers comprise recycled fibers.11. The method of any preceding or following embodiment/feature/aspect,wherein said organic contaminants comprise stickies.12. The method of any preceding or following embodiment/feature/aspect,wherein the ester hydrolyzing enzyme comprises lipase.13. The method of any preceding or following embodiment/feature/aspect,wherein at least one detackifier comprises at least one water-solublecellulose derivative.14. The method of any preceding or following embodiment/feature/aspect,wherein said water-soluble cellulose derivative comprises methylcellulose, hydroxyl methyl cellulose, hydroxyethyl methyl cellulose,hydropropyl methyl cellulose, cetyl hydroxyethylcellulose orhydroxybutyl methyl cellulose, singly or in any combination thereof.15. The method of any preceding or following embodiment/feature/aspect,wherein said fibers containing organic contaminants comprise fibers fromold corrugated containers, old newsprint or old newspapers, mixed officewaste, or any combinations thereof.16. The method of any preceding or following embodiment/feature/aspect,wherein the organic contaminants are at least controlled by reducing theamount of organic contaminants present in the fiber.17. The method of any preceding or following embodiment/feature/aspect,wherein the organic contaminants are at least controlled by reducing thesize of the organic contaminants present in the fibers.18. The method of any preceding or following embodiment/feature/aspect,wherein the organic contaminants are at least controlled by reducing thetackiness of the organic contaminants present in the fibers.19. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite, and optionally at least onedetackifier and/or at least one ester hydrolyzing enzyme are introducedprior to a pulping stage.20. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite, and optionally at least onedetackifier and/or at least one ester hydrolyzing enzyme are introducedduring a pulping stage.21. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite, and optionally at least onedetackifier and/or at least one ester hydrolyzing enzyme are introducedduring or right before a stock preparation stage.22. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite, and optionally at least onedetackifier and/or at least one ester hydrolyzing enzyme are introducedafter a flotation or a de-inking stage.23. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and optionally b) are in contact withthe fibers for a time of from about 1 minute to about 8 hours.24. The method of any preceding or following embodiment/feature/aspect,further comprising forming said fibers into paper or paperboardproducts.25. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and optionally b) are introduced priorto the paper machine headbox.26. The method of any preceding or following embodiment/feature/aspect,wherein said at least one zeolite and optionally b) are introduced inthe paper machine white water.27. The method of any preceding or following embodiment/feature/aspect,wherein said fibers comprise virgin fibers, said organic contaminantscomprise pitch and/or wood extractives.28. The method of any preceding or following embodiment/feature/aspect,wherein said liquid suspension further comprises lipoxygenase.29. The method of any preceding or following embodiment/feature/aspect,wherein the ester hydrolyzing enzyme comprises esterase, lipase, orcutinase, singly or in any combination thereof.30. The method of any preceding or following embodiment/feature/aspect,wherein said water-soluble cellulose derivative is a methyl ethercellulose derivative.31. A method for controlling organic contaminants from fibers in papermaking systems, comprising treating water in a clarifier or immediatelyprior to said clarifier with a) at least one zeolite and optionally b)at least one detackifier, or at least one ester hydrolyzing enzyme, orboth, for a sufficient time and in a sufficient amount to control theorganic contaminants present in said water.32. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is said at least one ester hydrolyzing enzyme.33. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is said at least one detackifier, and whereinsaid at least one zeolite and detackifier are present together as aliquid suspension and added to said water.34. The method of any preceding or following embodiment/feature/aspect,wherein b) is present and is said at least one detackifier and at leastone ester hydrolyzing enzyme, and wherein said at least one zeolite,detackifier and ester hydrolyzing enzyme are present together in aliquid suspension and added to said water.35. The method of any preceding or following embodiment/feature/aspect,wherein said water further comprises pulp fibers.36. The method of any preceding or following embodiment/feature/aspect,wherein said a) and b) are added separately to said fibers.

The present invention can include any combination of these variousfeatures or embodiments above and/or below as set forth in sentencesand/or paragraphs. Any combination of disclosed features herein isconsidered part of the present invention and no limitation is intendedwith respect to combinable features.

The present invention will be further clarified by the followingexamples, which are intended to be purely exemplary of the presentinvention, in which parts are proportions by weight unless otherwisespecified.

EXAMPLES

In the following tested samples, ethylene-vinyl acetate (EVA) as a modelof tack stickies was used as it is one of major components in recyclepulp contaminates. In the Examples, several variations of the presentinvention were tested and compared with comparative treatments orcontrols.

Example 1 Testing Procedure for Detackification Testing

Take 500 ml of tap water in 1000 ml beaker and place beaker on a hotplate with temperature control and magnetic agitation. UseEthylene-vinyl acetate (EVA) as a model of tack stickies. Warm up waterto designed temperature and add EVA into water at designedconcentration. Start agitation at designed speed for certain period oftime. Dilute the test samples and add in stickies solution underagitation, continue to agitate the mixture for designed time and removesamples from the hot plate. Place a black filter paper on a funnelfilter. Carefully filter the mixture of solution through the filterpaper. Remove the filter paper and dry it on a hot plate. Use a coatedpaper to cover on the filter paper and place them in a heated carverpress at 220° F. and 5000 psi for 2 minutes. Remove coated paper fromthe filter paper and use the filter paper for testing.

Stickies Counting:

Use a scanner to scan the filter paper and use Use Speck 2 software toanalyze the results. The results can be displayed as particle numbers(Count) and areas (PPM).

Testing Conditions:

-   -   Temperature: 120° F.    -   pH: 7.0    -   Contaminant Mix Time: 20 minutes    -   Product Mix Time: 40 minutes.

Results:

Tables 1 and 2 summarize the comparisons of various inorganic particlesand methylcellulose in detackification performance by using EVA as tackycompound. Zeolite shows better performance on reduction of tackymaterial deposition than the other mineral particles.

To better understand the results, the goal in effective organiccontaminant control (stickies control) is to reduce or avoid “large”contaminants (stickies) which can foul up a pulp/paper line, and afurther goal is to have “small” contaminants (stickies) if anycontaminants are going to be present, as these are far less likely tofoul up a pulp/paper line. In looking at the Tables, betters results arewhere the count for “large” contaminants is low/lower and the count for“medium” contaminants is low/lower, and the count for “small”contaminants is high/higher. As can be seen in Table 1, B, C, and D,were all effective in raising the “small” count compared to the“Control”. But, C and D were effective in lowering the “large” countcompared to the Control and C (Zeolite) was most effective in thisability even compared to D. This was also true for reducing the “medium”count.

In Table 2, where the amount of simulated stickies (EVA) was doubledcompared to Table 1, and the dosage was also doubled, the effects of thepresent invention (Sample L) were even more apparent in reducing allcounts and even the “small” count, which is surprising and impressive.

In all Tables (for sticky counting):

-   -   Small=0.01 to 0.1 mm²    -   Medium=greater than 0.1 mm² to 1.0 mm²    -   Large=greater than 1.0 mm² to 2.0 mm² and higher.

Detackification Testing:

TABLE 1 Comparison of performance of mineral particles ondetackification Group-1 EVA, 50 ppm, 300 rpm, 20/40 min, Dosage 25 ppm A(Control) B (Talc) C (Zeolite) D (BLX13826) Small 253 5061 1335 4824(Count) PPM 279 4772 1257 3888 Medium 121 589 121 246 (Count) PPM 12585422 996 2078 Large 33 42 11 18 (Count) PPM 3850 3584 817 2319 Control =water with EVA without any additive. Talc = suspended in water-forexample a 50 ppm dosage would be made by adding 0.05 g talc/L water.Zeolite = zeolite suspended in water—for example a 50 ppm dosage wouldbe made by adding 0.05 g zeolite/L water. (avg. particle size of zeolitein all examples was about 4.5 microns). BLX-13826 is a commercialproduct of Buckman Laboratories, Inc. (Memphis, TN) and is aDiatomaceous earth (DE)/Methycellulose formulation.

TABLE 2 Comparison of performance of mineral particles ondetackification Group-3 EVA, 100 ppm, 350 rpm, 20/40 min, Dosage 50 ppmI (Control) J (DE) K (Talc) L (Zeolite) Small 353 724 523 198 (Count)PPM 402 1171 781 254 Medium 158 1207 375 102 (Count) PPM 1760 14961 3920935 Large 39 170 73 2 (Count) PPM 3038 12815 6712 112

Table 3 and FIG. 1 show performance comparison of zeolite and zeolitecombination with dispersant or enzyme. The results indicate thecombination of zeolite and enzyme further improve the efficiency ofdetackification.

FIG. 1 also shows the comparison of a zeolite formulation with someexisting commercial non-zeolite containing products in detackificationefficiency. The zeolite formulation (Z-1) showed better performance thanexisting products at the same dosage condition.

As seen in Table 3, all of the zeolite formulations (M, N and O) wereeffective in reducing all contaminant counts (small, medium and large),again showing the effectiveness of the present invention.

TABLE 3 Comparison of performance of mineral particles ondetackification Group-4 EVA, 100 ppm, 350 rpm, 20/40 min, Dosage 50 ppmM (Zeolite/ N (Zeolite/ BSP248 90:10) NS51032 90:10) O (Zeolite) P(Control) Small 401 507 391 879 (Count) PPM 601 772 530 1074 Medium 370324 273 652 (Count) PPM 3795 3077 2606 7553 Large 43 26 44 99 (Count)PPM 4218 2798 3676 11917 BSP 248 = Busperse 248 product from BuckmanLaboratories, Inc and is a pitch control product that contains adispersant. NS51032 is a lipase product from Novozyme. Zeolite = zeolitesuspended in water—for example a 50 ppm dosage would be made by adding0.05 g zeolite/L water. Control = water and ppm amount of EVA.

-   -   In FIG. 1: (EVA concentration 100 ppm. Dosage lb/t: OPP745 50        ppm; OPP 525 25 ppm; BLX-13827 100 ppm; Z-1 50 ppm; OPP525/BSP        2281 and Z-1/BSP 2281:37.5 ppm). All dosages based on        as-received.    -   OPP 745=OPTIMYZE 745 product from Buckman Laboratories, Inc—a        lipase/surfactant mixture.    -   OPP 525=OPTIMYZE 525 product from Buckman Laboratories, Inc—a        stabilized lipase product.    -   BLX-13827=Diatomaceous earth with methylcellulose and lipase        enzyme (commercial product of Buckman Laboratories, Inc).    -   Z-1=Zeolite 12%, Methocel 1%, NS51032 1.5%, Resinase HT 0.5%,        Xanthan gum 0.4%, Propylene glycol 2.0%, Water 82.6%.    -   BSP 2281=BUSPERSE 2281 product from Buckman Laboratories, Inc is        a solvent/surfactant mixture.

Example 2 Pulmac Testing (Using Recycled Pulp)

Testing procedure for pulp stickies testing:

-   -   Pulmac Master Screen was used for stickies test for recycled        pulp.    -   Testing conditions: OCC pulp obtained from paper mill.    -   After screening, use coated paper to cover on black filter paper        and place them in a heated carver press at 220° F. and 5000 psi        for 3 minutes. Remove coated paper after heating press and use        the same stickies counting method as mentioned above for        stickies analysis.

Table 4 and FIG. 2 show the comparison of zeolite formulation with someexisting commercial non-zeolite containing products in stickiesreduction in pulp by using Pulmac testing. Zeolite formulation (Z-1)provided better efficiency on stickies reduction.

As can be seen in Table 4 and FIG. 4, the zeolite formulation (Z-1) hadalmost comparable reduction in “count” but more importantly was able toreduce the size of the stickies better than the enzymes alone or withDiatomaceous earth.

TABLE 4 Performance comparison of some products on stickies control byusing Pulmac testing. % Reduction of stickies OPP OPP BLX- 735 742 13827Z-1 Count 69% 65% 58% 57% PPM 81% 85% 81% 87% Size 38% 56% 55% 69% Note:All products used the same dosage level as received BLX-13827 isDE/Methycellulose/Enzyme formulation and Z-1 isZeolite/Methycellulose/Enzyme formulation. OPP 735 and OPP 742 areBuckman enzyme products.

The zeolite was Z-Ultra from ZEO Inc., and was used in the amount of 2.4pounds per dry ton of fiber. The methylcellulose detackifier wasMethocel F50 from Dow Chemical Co., and used in the amount of 0.6 poundper dry ton of fiber. The enzyme(s) was NS51032 and Resinase HT fromNovozyme used in the amount of 0.26 pound per dry ton of fiber.

In Example 2, a machine chest stock resulting from used hot melt glued,single wall corrugated containers was obtained from a mill and hadapproximately 3 to about 5% by weight consistency of fibers or solids.This stock was then diluted to a 1% by weight consistency the pH wasadjusted to 7.4 and then heated to approximately 50 to 60° C. 1,000milliliter samples of the dilute stock were then placed on a hot plateto maintain the 50 to 60° C. temperature and the dilute stock was mixedat a constant rate of approximately 100-150 rpm. Then, one of theTreatments listed above was used, and the resulting different sampleswere mixed for 1 to 2 hours. The compositions tested are identified asabove for purposes of this example.

The samples were then diluted to 10 liters by introducing water and thenthese samples were screened through a Pulmac Masterscreen using a 0.004inch screen. The contaminants collected on the filter pad were dried inan oven. A clean piece of black filter paper and unused calciumcarbonate coated paper with the calcium carbonate in contact with thecollection pad was placed on top of the collection pad and the pieceswere then placed on a Carver Press and pressed for 3 minutes at 220° F.(105° C.) at a pressure of 5,000 psi. The top filter and the calciumcarbonate coated paper was then peeled off and the amount ofcontaminants by counts and ppm were measured using an Optimax FlatbedScanner. This same set-up was used to determine the “Counts” as ppms.

Applicants specifically incorporate the entire contents of all citedreferences in this disclosure. Further, when an amount, concentration,or other value or parameter is given as either a range, preferred range,or a list of upper preferable values and lower preferable values, thisis to be understood as specifically disclosing all ranges formed fromany pair of any upper range limit or preferred value and any lower rangelimit or preferred value, regardless of whether ranges are separatelydisclosed. Where a range of numerical values is recited herein, unlessotherwise stated, the range is intended to include the endpointsthereof, and all integers and fractions within the range. It is notintended that the scope of the invention be limited to the specificvalues recited when defining a range.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments of thepresent invention without departing from the spirit or scope of thepresent invention. Thus, it is intended that the present inventioncovers other modifications and variations of this invention providedthey come within the scope of the appended claims and their equivalents.

What is claimed is:
 1. A method for controlling deposition of organiccontaminants from fibers in paper making systems, comprising contactingsaid fibers with a) at least one zeolite and optionally b) at least onedetackifier, or at least one ester hydrolyzing enzyme or both, for asufficient time and in a sufficient amount to control the organiccontaminants present in the fibers.
 2. The method of claim 1, wherein b)is present and is said at least one ester hydrolyzing enzyme.
 3. Themethod of claim 1, wherein b) is present and is at least onedetackifier.
 4. The method of claim 1, wherein b) is present and is atleast one ester hydrolyzing enzyme and at least one detackifier.
 5. Themethod of claim 3, wherein said at least one zeolite and detackifier arepresent together as a liquid suspension and added to a pulp slurrycontaining said fibers.
 6. The method of claim 4, wherein said at leastone zeolite, detackifier, and ester hydrolyzing enzyme are presenttogether in a liquid suspension and added to a pulp slurry containingsaid fibers.
 7. The method of claim 2, wherein said at least one zeoliteand ester hydrolyzing enzyme are present together in a liquid suspensionand added to a pulp slurry containing said fibers.
 8. The method ofclaim 1, wherein said at least one zeolite and optionally b) are addedto a pulp slurry containing said fibers prior to a forming stage.
 9. Themethod of claim 1, wherein said organic contaminants comprise syntheticpolymers from adhesives, glues, hot-melts, coatings, coating binders,de-inking chemicals, ink residues, wood resins, rosin, contact adhesivebinders, unpulped wet strength resins, pitch, or combinations thereof.10. The method of claim 1, wherein said fibers comprise recycled fibers.11. The method of claim 1, wherein said organic contaminants comprisestickies.
 12. The method of claim 1, wherein the ester hydrolyzingenzyme comprises lipase.
 13. The method of claim 1, wherein at least onedetackifier comprises at least one water-soluble cellulose derivative.14. The method of claim 13, wherein said water-soluble cellulosederivative comprises methyl cellulose, hydroxyl methyl cellulose,hydroxyethyl methyl cellulose, hydropropyl methyl cellulose, cetylhydroxyethylcellulose or hydroxybutyl methyl cellulose, singly or in anycombination thereof.
 15. The method of claim 1, wherein said fiberscontaining organic contaminants comprise fibers from old corrugatedcontainers, old newsprint or old newspapers, mixed office waste, or anycombinations thereof.
 16. The method of claim 1, wherein the organiccontaminants are at least controlled by reducing the amount of organiccontaminants present in the fiber.
 17. The method of claim 1, whereinthe organic contaminants are at least controlled by reducing the size ofthe organic contaminants present in the fibers.
 18. The method of claim1, wherein the organic contaminants are at least controlled by reducingthe tackiness of the organic contaminants present in the fibers.
 19. Themethod of claim 1, wherein said at least one zeolite, and optionally atleast one detackifier and/or at least one ester hydrolyzing enzyme areintroduced prior to a pulping stage.
 20. The method of claim 1, whereinsaid at least one zeolite, and optionally at least one detackifierand/or at least one ester hydrolyzing enzyme are introduced during apulping stage.
 21. The method of claim 1, wherein said at least onezeolite, and optionally at least one detackifier and/or at least oneester hydrolyzing enzyme are introduced during or right before a stockpreparation stage.
 22. The method of claim 1, wherein said at least onezeolite, and optionally at least one detackifier and/or at least oneester hydrolyzing enzyme are introduced after a flotation or a de-inkingstage.
 23. The method of claim 1, wherein said at least one zeolite andoptionally b) are in contact with the fibers for a time of from about 1minute to about 8 hours.
 24. The method of claim 1, further comprisingforming said fibers into paper or paperboard products.
 25. The method ofclaim 1, wherein said at least one zeolite and optionally b) areintroduced prior to the paper machine headbox.
 26. The method of claim1, wherein said at least one zeolite and optionally b) are introduced inthe paper machine white water.
 27. The method of claim 1, wherein saidfibers comprise virgin fibers, said organic contaminants comprise pitchand/or wood extractives
 28. The method of claim 6, wherein said liquidsuspension further comprises lipoxygenase.
 29. The method of claim 1,wherein the ester hydrolyzing enzyme comprises esterase, lipase, orcutinase, singly or in any combination thereof.
 30. The method of claim1, wherein said water-soluble cellulose derivative is a methyl ethercellulose derivative.
 31. A method for controlling organic contaminantsfrom fibers in paper making systems, comprising treating water in aclarifier or immediately prior to said clarifier with a) at least onezeolite and optionally b) at least one detackifier, or at least oneester hydrolyzing enzyme, or both, for a sufficient time and in asufficient amount to control the organic contaminants present in saidwater.
 32. The method of claim 31, wherein b) is present and is said atleast one ester hydrolyzing enzyme.
 33. The method of claim 31, whereinb) is present and is said at least one detackifier, and wherein said atleast one zeolite and detackifier are present together as a liquidsuspension and added to said water.
 34. The method of claim 31, whereinb) is present and is said at least one detackifier and at least oneester hydrolyzing enzyme, and wherein said at least one zeolite,detackifier and ester hydrolyzing enzyme are present together in aliquid suspension and added to said water.
 35. The method of claim 31,wherein said water further comprises pulp fibers.
 36. The method ofclaim 1, wherein said a) and b) are added separately to said fibers.